1. Field of the Invention
This invention relates to a method for the manufacture of a vinyl chloride copolymer solution, and more particularly to a method for the manufacture of a solution of a vinyl chloride-vinyl ester-vinyl alcohol ternary copolymer wherein a vinyl chloride-vinyl ester copolymer is hydrolyzed with an acid or alkali in the presence of alcohol and then the alcohol content is reduced to less than 0.5 wt%.
2. Description of the Prior Art
Heretofore, there has been known a ternary copolymer consisting of vinyl chloride, vinyl ester and vinyl alcohol. This ternary copolymer is usually manufactured by a method in which a vinyl chloride-vinyl ester copolymer is supended in alcohol and hydrolyzed with an acid or alkali and then the alcohol is removed by filtering it from the hydrolyzed product, or a method in which the vinyl chloride-vinyl ester copolymer is dissolved in an organic solvent, alcohol is added thereto, hydrolyzation is carried out with an acid or alkali and then a solvent is added to precipitate the hydrolyzed product. In the case where the hydrolyzed product obtained by such a method is used as a paint, adhesive, ink or the like, however, it must be disolved again in an organic solvent before use; therefore, it would be convenient if the ternary copolymer can be used as it is without involving any other complicated steps. But the ternary copolymer contains a large quantity of alcohol, so that when the copolymer is mixed, for example, in an urethane resin, the latter reacts with the alcohol to destroy such features of the ternary copolymer as solvent resistance, adhesiveness, softness and luster afforded by its three-dimensional structure; therefore, removal of the alcohol is desired.